linux/tools/bpf/bpftool, branch master

bpftool: add missing fsession to the usage and docs of bpftool

2026-04-12T19:42:38Z

Add the fsession attach type to the usage of bpftool in do_help(). Meanwhile, add it to the bash-completion and bpftool-prog.rst too. Acked-by: Leon Hwang Acked-by: Quentin Monnet Signed-off-by: Menglong Dong Link: https://lore.kernel.org/r/20260412060346.142007-4-dongml2@chinatelecom.cn Signed-off-by: Alexei Starovoitov

bpftool: Enable aarch64 ISA extensions for JIT disassembly

2026-03-24T15:44:29Z

The LLVM disassembler needs ISA extension features enabled to correctly decode instructions from those extensions. On aarch64, without these features, instructions like LSE atomics (e.g. ldaddal) are silently decoded as incorrect instructions and disassembly is truncated. Use LLVMCreateDisasmCPUFeatures() with "+all" features for aarch64 targets so that the disassembler can handle any instruction the kernel JIT might emit. Before: int bench_trigger_uprobe(void * ctx): bpf_prog_538c6a43d1c6b84c_bench_trigger_uprobe: ; int cpu = bpf_get_smp_processor_id(); 0: mov x9, x30 4: nop 8: stp x29, x30, [sp, #-16]! c: mov x29, sp 10: stp xzr, x26, [sp, #-16]! 14: mov x26, sp 18: mrs x10, SP_EL0 1c: ldr w7, [x10, #16] ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 20: and w7, w7, #0xff ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 24: lsl x7, x7, #7 28: mov x0, #-281474976710656 2c: movk x0, #32768, lsl #32 30: movk x0, #35407, lsl #16 34: add x0, x0, x7 38: mov x1, #1 ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 3c: mov x1, #1 After: int bench_trigger_uprobe(void * ctx): bpf_prog_538c6a43d1c6b84c_bench_trigger_uprobe: ; int cpu = bpf_get_smp_processor_id(); 0: mov x9, x30 4: nop 8: stp x29, x30, [sp, #-16]! c: mov x29, sp 10: stp xzr, x26, [sp, #-16]! 14: mov x26, sp 18: mrs x10, SP_EL0 1c: ldr w7, [x10, #16] ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 20: and w7, w7, #0xff ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 24: lsl x7, x7, #7 28: mov x0, #-281474976710656 2c: movk x0, #32768, lsl #32 30: movk x0, #35407, lsl #16 34: add x0, x0, x7 38: mov x1, #1 ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 3c: ldaddal x1, x1, [x0] ; return 0; 40: mov w7, #0 44: ldp xzr, x26, [sp], #16 48: ldp x29, x30, [sp], #16 4c: mov x0, x7 50: ret 54: nop 58: ldr x10, #8 5c: br x10 Signed-off-by: Puranjay Mohan Acked-by: Yonghong Song Acked-by: Leon Hwang Acked-by: Quentin Monnet Reviewed-by: Emil Tsalapatis Link: https://lore.kernel.org/r/20260318172259.2882792-1-puranjay@kernel.org Signed-off-by: Alexei Starovoitov

bpftool: Allow explicitly skip llvm, libbfd and libcrypto dependencies

2026-03-16T21:14:14Z

Introduce SKIP_LLVM, SKIP_LIBBFD, and SKIP_CRYPTO build flags that let users build bpftool without these optional dependencies. SKIP_LLVM=1 skips LLVM even when detected. SKIP_LIBBFD=1 prevents the libbfd JIT disassembly fallback when LLVM is absent. Together, they produce a bpftool with no disassembly support. SKIP_CRYPTO=1 excludes sign.c and removes the -lcrypto link dependency. Inline stubs in main.h return errors with a clear message if signing functions are called at runtime. Use BPFTOOL_WITHOUT_CRYPTO (not HAVE_LIBCRYPTO_SUPPORT) as the C define, following the BPFTOOL_WITHOUT_SKELETONS naming convention for bpftool-internal build config, leaving HAVE_LIBCRYPTO_SUPPORT free for proper feature detection in the future. All three flags are propagated through the selftests Makefile to bpftool sub-builds. Signed-off-by: Mykyta Yatsenko Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260312-b4-bpftool_build-v2-1-4c9d57133644@meta.com

bpftool: Support merging multiple module BTFs in btf dump

2026-03-05T23:03:02Z

Add support for specifying multiple file sources in 'bpftool btf dump' to generate a single C header containing types from vmlinux plus multiple kernel modules: bpftool btf dump file /sys/kernel/btf/mod1 file /sys/kernel/btf/mod2 format c This is useful for BPF programs that need to access types defined in kernel modules. Previously this required a separate bpftool invocation for each module, producing separate headers that could not be combined due to overlapping vmlinux type definitions. The implementation collects all file paths, then for the multi-file case creates an empty split BTF on the vmlinux base and iteratively merges each module's types into it via btf__add_btf(). The single-file code path is preserved exactly to avoid any regression risk. Auto-detection of vmlinux as the base BTF from sysfs paths works as before. If vmlinux itself appears in the file list it is skipped with a warning since its types are already provided by the base. Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Josef Bacik Signed-off-by: Andrii Nakryiko Reviewed-by: Alan Maguire Link: https://lore.kernel.org/bpf/b19c2760ffe48cec546dd3810d237f8cad20d606.1772657690.git.josef@toxicpanda.com

bpftool: Fix truncated netlink dumps

2026-02-18T00:54:03Z

Netlink requires that the recv buffer used during dumps is at least min(PAGE_SIZE, 8k) (see the man page). Otherwise the messages will get truncated. Make sure bpftool follows this requirement, avoid missing information on systems with large pages. Acked-by: Quentin Monnet Fixes: 7084566a236f ("tools/bpftool: Remove libbpf_internal.h usage in bpftool") Signed-off-by: Jakub Kicinski Link: https://lore.kernel.org/r/20260217194150.734701-1-kuba@kernel.org Signed-off-by: Alexei Starovoitov

bpftool: Fix dependencies for static build

2026-01-28T21:26:41Z

When building selftests/bpf with EXTRA_LDFLAGS=-static the follwoing error happens: LINK /ws/linux/tools/testing/selftests/bpf/tools/build/bpftool/bootstrap/bpftool /usr/bin/x86_64-linux-gnu-ld.bfd: /usr/lib/gcc/x86_64-linux-gnu/15/../../../x86_64-linux-gnu/libcrypto.a(libcrypto-lib-dso_dlfcn.o): in function `dlfcn_globallookup': [...] /usr/bin/x86_64-linux-gnu-ld.bfd: /usr/lib/gcc/x86_64-linux-gnu/15/../../../x86_64-linux-gnu/libcrypto.a(libcrypto-lib-c_zlib.o): in function `zlib_oneshot_expand_block': (.text+0xc64): undefined reference to `uncompress' /usr/bin/x86_64-linux-gnu-ld.bfd: /usr/lib/gcc/x86_64-linux-gnu/15/../../../x86_64-linux-gnu/libcrypto.a(libcrypto-lib-c_zlib.o): in function `zlib_oneshot_compress_block': (.text+0xce4): undefined reference to `compress' collect2: error: ld returned 1 exit status make[1]: *** [Makefile:252: /ws/linux/tools/testing/selftests/bpf/tools/build/bpftool/bootstrap/bpftool] Error 1 make: *** [Makefile:327: /ws/linux/tools/testing/selftests/bpf/tools/sbin/bpftool] Error 2 make: *** Waiting for unfinished jobs.... This is caused by wrong order of dependencies in the Makefile. Fix it. Signed-off-by: Ihor Solodrai Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260128211255.376933-1-ihor.solodrai@linux.dev

bpftool: add fsession support

2026-01-25T02:49:36Z

Add BPF_TRACE_FSESSION to bpftool. Signed-off-by: Menglong Dong Link: https://lore.kernel.org/r/20260124062008.8657-10-dongml2@chinatelecom.cn Signed-off-by: Alexei Starovoitov

bpftool: Add 'prepend' option for tcx attach to insert at chain start

2026-01-16T22:51:23Z

Add support for the 'prepend' option when attaching tcx_ingress and tcx_egress programs. This option allows inserting a BPF program at the beginning of the TCX chain instead of appending it at the end. The implementation uses BPF_F_BEFORE flag which automatically inserts the program at the beginning of the chain when no relative reference is specified. This change includes: - Modify do_attach_tcx() to support prepend insertion using BPF_F_BEFORE - Update documentation to describe the new 'prepend' option - Add bash completion support for the 'prepend' option on tcx attach types - Add example usage in the documentation - Add validation to reject 'overwrite' for non-XDP attach types The 'prepend' option is only valid for tcx_ingress and tcx_egress attach types. For XDP attach types, the existing 'overwrite' option remains available. Example usage: # bpftool net attach tcx_ingress name tc_prog dev lo prepend This feature is useful when the order of program execution in the TCX chain matters and users need to ensure certain programs run first. Co-developed-by: Siwan Kim Signed-off-by: Siwan Kim Signed-off-by: Gyutae Bae Signed-off-by: Andrii Nakryiko Reviewed-by: Quentin Monnet Acked-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20260112034516.22723-1-gyutae.opensource@navercorp.com

bpftool: Make skeleton C++ compatible with explicit casts

2026-01-09T19:01:54Z

Fix C++ compilation errors in generated skeleton by adding explicit pointer casts and use char * subtraction for offset calculation error: invalid conversion from 'void*' to '*' [-fpermissive] | skel = skel_alloc(sizeof(*skel)); | ~~~~~~~~~~^~~~~~~~~~~~~~~ | | | void* error: arithmetic on pointers to void | skel->ctx.sz = (void *)&skel->links - (void *)skel; | ~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~ error: assigning to 'struct __ *' from incompatible type 'void *' | skel-> = skel_prep_map_data((void *)data, 4096, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | sizeof(data) - 1); | ~~~~~~~~~~~~~~~~~ error: assigning to 'struct __ *' from incompatible type 'void *' | skel-> = skel_finalize_map_data(&skel->maps..initial_value, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | 4096, PROT_READ | PROT_WRITE, skel->maps..map_fd); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Minimum reproducer: $ cat test.bpf.c int val; // placed in .bss section #include "vmlinux.h" #include SEC("raw_tracepoint/sched_wakeup_new") int handle(void *ctx) { return 0; } $ cat test.cpp #include extern "C" { #include "test.bpf.skel.h" } $ bpftool btf dump file /sys/kernel/btf/vmlinux format c > vmlinux.h $ clang -g -O2 -target bpf -c test.bpf.c -o test.bpf.o $ bpftool gen skeleton test.bpf.o -L > test.bpf.skel.h $ g++ -c test.cpp -I. Co-developed-by: Menglong Dong Signed-off-by: WanLi Niu Signed-off-by: Menglong Dong Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260106023123.2928-1-kiraskyler@163.com

bpftool: Fix build warnings due to MS extensions

2025-12-10T07:21:33Z

The kernel is now built with -fms-extensions. Anonymous structs or unions permitted by these extensions have been used in several places, and can end up in the generated vmlinux.h file, for example: struct ns_tree { [...] }; [...] struct ns_common { [...] union { struct ns_tree; struct callback_head ns_rcu; }; }; Trying to include this header for compiling a tool may result in build warnings, if the compiler does not expect these extensions. This is the case, for example, with bpftool: In file included from skeleton/pid_iter.bpf.c:3: .../tools/testing/selftests/bpf/tools/build/bpftool/vmlinux.h:64057:3: warning: declaration does not declare anything [-Wmissing-declarations] 64057 | struct ns_tree; | ^~~~~~~~~~~~~~ Fix these build warnings in bpftool by turning on Microsoft extensions when compiling the two BPF programs that rely on vmlinux.h. Reported-by: Alexei Starovoitov Closes: https://lore.kernel.org/bpf/CAADnVQK9ZkPC7+R5VXKHVdtj8tumpMXm7BTp0u9CoiFLz_aPTg@mail.gmail.com/ Signed-off-by: Quentin Monnet Link: https://lore.kernel.org/r/20251208130748.68371-1-qmo@kernel.org Signed-off-by: Alexei Starovoitov